Helicobacter pylori is distinguished by high genetic diversity which can be explained by a long evolutionary history as well as the ability of horizontal gene transfer. Among H. pylori virulence factors, cagA gene owing four EPIYA motifs (A, B, C , and D) is highly prone to genetic rearrangement which could have great impact on clinical outcomes. In the present study paired formalin- fixed and paraffin-embedded (FFPE) gastric tissues which were obtained from 30 H. pylori-positive patients with 10-years interval were recruited to examine the changes in H. pylori cag A motif by time.

Paired FFPE gastric biopsies were obtained from 30 H. pylori positive patients which were 10 years apart from archive of pathology department of digestive disease research institute Tehran, Iran. After DNA extraction, presence of H. pylori was assessed by PCR amplification of H. pylori16S rRNA gene. Presence of cagA and type of EPIYA motifs was determined by PCR using cagA motifs-specific primers.

All the recruited samples carried H pylori 16S rRNA gene. In 8/30 patients no variation was observed in the motif pattern of cag A while there has been significant changes in remaining 22 patients. In 11 /30 patients, at least one motif was removed from second sample comparing to primary sample while in 11/30 patients at least one more motif was observed in secondary samples. Overall variation in EPIYA motif-C was the dominant change observed between paired samples.

Results of this study revealed a remarkable heterogeneity in EPIYA motif pattern of cagA gene specially motif-C in individual hosts during time. Considering the relation between number and organization of cagA motif with H. pylori pathogenicity, further study could elucidate the impact of observed variation on disease status.